1. Field of the Invention
The present invention relates to an output circuit which outputs an analog signal and a current sensor having the output circuit, and particularly, to an output circuit in which the range of an output voltage is limited.
2. Description of the Related Art
There is a case in which an output voltage of an amplification circuit, a buffer circuit, or the like needs to be limited to a constant range. In this case, a voltage limiter circuit is used in general. FIG. 9 is a diagram illustrating a configuration of a general voltage limiter circuit of the related art (refer to Japanese Unexamined Patent Application Publication No. 2000-56841). The voltage limiter circuit 100 illustrated in FIG. 9 is configured by a diode 102 and a constant voltage source 103 which are connected in series to each other, and is connected to an output terminal of a buffer circuit 101 configured by an operational amplifier. If an output voltage Vout of the buffer circuit 101 reaches a voltage corresponding to a sum of a voltage of the constant voltage source 103 and a forward voltage of the diode 102, the diode 102 is turned on, a current flowing through the constant voltage source 103 increases, and thereby an increase in the output voltage Vout is limited.
In the voltage limiter circuit 100 illustrated in FIG. 9, a large current flows into the constant voltage source 103 through the diode 102 which is turned on, and thereby an increase in the voltage is limited. However, if an output circuit includes a circuit type with a high current supply capability, such as a push-pull type, an extremely large current flows through the voltage limiter circuit, and thus problems occur in which current consumption increases or an element temperature increases. In addition, since a forward voltage of a diode is greatly varied by temperature, there is also a problem in which the limitation range of an output voltage is changed by temperature.